Hi guys i know this topic has been around but i like to clarify some questions.

Below is the pic of the Porsche Sport Exhaust.

-appears to have 2 connecting pipes
1) between inlet,outlet
2)between the end of the box and the outlet pipe

Original





Next is Gundo's Sport Exhaust hack

- just a sngle connecting pipe between inlet and outlet

Works similar to partial bypass as some of the gas will bypass the muffler and return to the outlet which produce the higher noise.

however some bros who have done this have commented that the improved and louder sound is produced during harder acceleration and at higher revs.

I think this make sense as during startup, and low revs, the gas will still flow as uusal into the muffler box first.

Now looking at the picture, the angle of the connecting pipe i think affects the way the gas flows.

Notice that the pipe is at an angle. The part connected to the inlet is lower than the outlet
A)
Soundclip:[media]http://hk.youtube.com/watch?v=525WgBfvL9Y[/media]





Compare to another pic i found.. seems that the connecting pipe is rather levelled.

B)


Not sure the noise difference for this too

So my question is which angle constitute to a better noise at startup and low revs?

I personally think a 'Y' type pipe is best to split the gas and produce a more balanced partial bypass even at low revs,

C) Perhaps the most accurate representation of the the real PSE?



This mimics the PSE as it has dual outlet pipes




D) Similar to 'C' design but addiotion of bypass connecting pipes

Is this the loudest design?

http://hk.youtube.com/watch?v=PkEPZp...eature=related


cant find the soundclip for this one on 997s ..

Question is what is the purpose of the additional outlet pipe on the extreme left ? Does it create better noise at low revs/idle?

Also, the connecting pipe between this additional pipe is linked above the other connecting pipe?

I suppose this is to prevent any clash on the inflow and out flow?

Looking at the original PSE, i see that there seem to be also this additional outlet pipe.

So, which is the more accurate hack design?

A, B ,C or D?


The original PSE has lots of burble compared to the exhaust hack as far as i hear from youtube sources.


How do we create this idle noise.

 

I dont think anyone is doing R&D on exhaust hacks. Some of the solutions are just easier to do than others, or maybe the muffler shop didnt have a tube notcher so they just did the j pipe method.

The muffler is a 3 chamber design on the stock (non-pse) muffler. Not sure if the PSE is the same. Tapping into the 3rd chamber must sound different than just connecting the inlet and outlet tubes.

Either way its a cheap way to get good sound. Happy experimenting.

dr

 

I haven't ever done one on a 997, but have done plenty on the 993's. We used a more vertical attachment like Picture B, and the sound is incredible. A nice deep burble at idle, and a great exhaust note when driving, but not overly loud. For $20 in pipe, and $100 at the local welding shop, and the effort is well worth it. And, if you for some reason don't like it, well, you aren't out $1000 for aftermarket cans.

 

thanks for the response.

I am thinking you mention vertical and rightly so since once the mufflers are up, the are vertical.

My photo though shows it, at an angle.. I am thinking whether the angle of this pipe affects the gas flow

I would assume more gas flow would produce louder.

What setup you think would produce the most airflow?

And what size pipe you think should be used? i also assume the larger the louder

 

We used 2" stainless pipe. Yea, vertical as when installed. I thought your picture B looked like it was more straight up and down than the first picture which is obviously at an angle. It looks like it is a little tighter fit on the 997 to get it straight up and down. The 993 allows a little more room for this.

 

do you think vertical affects the sound at all?

 

This is the 1st time I'm seeing this thread. Just had Gundo hack put on my car last week. I had a 2" pipe welded between inlet/outlet...no pipe from the other end. Had the bridge pipe welded at a right angle from inlet pipe. So, I think only on a change in engine speed you will get a response, b/c you're applying higher pressure thru that connecting pipe. As the air leaves the muffler all I can figure is it has to be a lot lower pressure than when it went in (sound IS pressure and the muffler is designed to remove it).

I think if you made the connecting pipe more in line with the outlet, you wouldn't get as much sound, and if you made it more towards the muffler you might backflow into the muffler, which would be bad, IMO.

Interesting stuff. I would believe the true PSE is a bit louder since it has two outlets (two sound sources is louder than one), but not appreciably since you have the high pressure from inlet mixing with the low pressure from the other outlet pipe.

 

and I bet being vertical vs. horizontal when mounted in the car makes no difference whatsoever.

 

So what's the concencus??

Is there a particular design that is better then the rest... I'm thinking of doing this and would like to take a pic and have a welder duplicate it.

 

I like FD Motorsports' cost/design/sound. Is that the same as a Gundo hack?